Camshaft recommendations
 

Hi, I’m in the process of rebuilding the engines in a 1977 Scarab I bought. The previous owner swapped out the stock cams for Crane HMV-278-2A cams with single springs, as a result one engine ended up dropping an exhaust value and causing quite a bit of damage.

The engines are 454 Cyclone 400’s with a forged bottom end and rectangular port heads. Are the stock 400 cams any good? Should I go roller? Any recommendations would be greatly appreciated.

Thanks,
Dave

Stock 400 cams are decent. Same cam as the 420, 425, and 525SC. Its a Crane 132561.

http://store.summitracing.com/partde...1&autoview=sku

Nearly the same cam from Crane is a 134241 and it available in a kit (134242) with lifters for $100 less than the stock cam alone. Specs are very close.

http://store.summitracing.com/partde...2&autoview=sku

Thanks for the info. I'm used to working on automotive engines, and the stock 400 cam just seems too small to me for a rectangular port big block.

The stock 400 cam from Crane is a little on the pricey side, if I'm going to spend that much on a hydralic flat tappet cam maybe I should look into a custom grind?

I was originally thinking about trying this cam http://store.summitracing.com/partde...3&autoview=sku

It's cheap enough and if it's too big I could just throw it away and try something else. :)

That cam has too much duration. You will loose torque where you need it.

The second cam I listed is plenty large enough. I had one in a 454 Mag and it pulled strong to 5400-5500rpms. It will make 425hp+ . Mill the heads .030 and run a holley 800carb on an airgap intake.

BTW, you will also need good exhaust to make power and prevent reversion.

Another option you have would be to consult with OSO member "RMBuilder"/Bob Madara of Marine Kinetics. He's a stand up guy and extremely knowledgable with marine offshore/performance engines, and for about $60-70 more Bob will take all your engine's info and will have a cam custom ground for YOUR application, RPM range, etc. and you will be happy. He has done numerous sucessful marine cam applications for guys here for several years now. Bob's office is located in New York and can be reached at 585-654-8583. Have fun.

With an upgraded cam and old (1977?)Merc exhaust I'd look into possible water reversion and/or intrusion possibly causing that exhaust valve failure.

If you don't have OE exhaust from that era, mention what exhaust it does have.

The biggest hurdle when jumping from automotive to marine engines is the damn water cooled exhausts. Exhaust water reversion and/or intrusion is very real issue that is mostly effected by exhaust system and camshaft. Many other influences, but those two are by fat the largest.

As Kaama mentioned, RM does many perf marine cams and has many years of data.

HP 500 upgrade
 

are those crane cam grinds for HP500? what is a modest ugrade from a stock HP500 carb

anyone with knowledge?
Thanks

The Crane 731 cam is the one I've read is used in the 500 EFI motors, and is a step up from the HP 500 (carbed) cams. Then there's the 741, which a LOT of people like.

That was one of my concerns. I'd like be able to turn enough RPM but not totally kill the low end torque. I know I'm asking for a lot...:)
That's about what I'm shooting for around 425-450hp. I would like to try to salvage the Q-Jet and stock intake manifold if I can.
The engines had the old style log manifolds, riser in the rear, with a 3" outlet. I'm planning on replacing them the Revolution Marine exhaust manifolds.

Thanks, I've been reading though the prior posts on camshafts on the forum and Bob definately knows his stuff. :)